1. Field of the Invention
This invention relates generally to material handling systems. More particularly, the present invention is a row sweep system for a palletizer of a material-handling system.
2. Discussion of the Related Art
Palletizers of material-handling systems form groups of products and load the groups onto pallets. This may be done by way of, for example, bulk grouping or case grouping of products and transferring the groups onto pallets. Sweep systems are known for pushing groups of products from one station to another or onto a pallet or a pallet-loading device at the palletizer. Some sweep systems use reciprocating arms to push the products in one direction and then return to a home position in an opposite direction. These reciprocating systems take time to reciprocate back and forth, which can limit the speed at which product can be moved through the palletizer and can require complex controls to achieve the back-and-forth motion. Attempts have been made to use looping-type sweep arms that travel completely around stations of the palletizer so that the sweep arms can be driven in a single direction to return to the home position, which can simplify the controls and reduce the amount of time to return to the home positions. A looping-type sweep arm is typically driven from a single chain, with the sweep arm supported from a bracket(s) that is cantilevered from the chain to extend beyond the station and allow the rotation of the sweep arm around the station. However, even when these single chain-type drive systems are driven at a constant speed, the sweep arms tend to speed up through the corners in a manner that can cause extreme inertial forces and unwanted momentum as the sweep arms travel through the corners while rotating around the station. This is because, when rounding or traveling through a corner during equal time intervals, a sweep arm carried by a single chain-type drive system has to travel distances that increase per equal time interval while passing through an apex of the corner. This leads to the sweep arm experiencing a substantial acceleration spike while entering the corner and a substantial deceleration spike while exiting the corner, which can increase wear rate of system components and can cause unwanted whipping characteristics to the movement of the sweep arm.